Rishabh Dixit, Mert Gürbüzbalaban, Waheed U. Bajwa
{"title":"Accelerated Gradient Methods for Nonconvex Optimization: Escape Trajectories From Strict Saddle Points and Convergence to Local Minima","authors":"Rishabh Dixit, Mert Gürbüzbalaban, Waheed U. Bajwa","doi":"10.1007/s10208-026-09745-x","DOIUrl":"https://doi.org/10.1007/s10208-026-09745-x","url":null,"abstract":"This paper considers the problem of understanding the behavior of a general class of accelerated gradient methods on smooth nonconvex functions. Motivated by some recent works that have proposed effective algorithms, based on Polyak’s heavy ball method and the Nesterov accelerated gradient method, to achieve convergence to a local minimum of nonconvex functions, this work proposes a broad class of Nesterov-type accelerated methods and puts forth a rigorous study of these methods encompassing the escape from saddle points and convergence to local minima through both an asymptotic and a non-asymptotic analysis. In the asymptotic regime, this paper answers an open question of whether Nesterov’s accelerated gradient method (NAG) with variable momentum parameter avoids strict saddle points almost surely. This work also develops two metrics of asymptotic rates of convergence and divergence, and evaluates these two metrics for several popular standard accelerated methods such as the NAG and Nesterov’s accelerated gradient with constant momentum (NCM) near strict saddle points. In the non-asymptotic regime, this work provides an analysis that leads to the “linear” exit time estimates from strict saddle neighborhoods for trajectories of these accelerated methods as well the necessary conditions for the existence of such trajectories. Finally, this work studies a sub-class of accelerated methods that can converge in convex neighborhoods of nonconvex functions with a near optimal rate to a local minimum and at the same time this sub-class offers superior saddle-escape behavior compared to that of NAG.","PeriodicalId":55151,"journal":{"name":"Foundations of Computational Mathematics","volume":"64 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147586722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Crouzeix-Raviart elements on simplicial meshes in d dimensions","authors":"Nis-Erik Bohne, Patrick Ciarlet, Stefan Sauter","doi":"10.1007/s10208-026-09741-1","DOIUrl":"https://doi.org/10.1007/s10208-026-09741-1","url":null,"abstract":"","PeriodicalId":55151,"journal":{"name":"Foundations of Computational Mathematics","volume":"94 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147359908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Nearly Self-similar Blowup of Generalized Axisymmetric Navier–Stokes Equations","authors":"Thomas Y. Hou","doi":"10.1007/s10208-026-09748-8","DOIUrl":"https://doi.org/10.1007/s10208-026-09748-8","url":null,"abstract":"","PeriodicalId":55151,"journal":{"name":"Foundations of Computational Mathematics","volume":"81 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147287094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Extended Regge Complex for Linearized Riemann-Cartan Geometry and Cohomology","authors":"Snorre H. Christiansen, Kaibo Hu, Ting Lin","doi":"10.1007/s10208-026-09746-w","DOIUrl":"https://doi.org/10.1007/s10208-026-09746-w","url":null,"abstract":"We show that the cohomology of the Regge complex in three dimensions is isomorphic to <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ mathcal {H}^{{scriptscriptstyle bullet }}_{dR}(varOmega )otimes mathcal{R}mathcal{M}$$</jats:tex-math> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>dR</mml:mi> </mml:mrow> <mml:mstyle> <mml:mo>∙</mml:mo> </mml:mstyle> </mml:msubsup> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>Ω</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>⊗</mml:mo> <mml:mi>R</mml:mi> <mml:mi>M</mml:mi> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> , the de Rham cohomology of differential forms with values in infinitesimal rigid body motions. Based on an observation that the twisted de Rham complex extends the elasticity complex (based on Riemannian deformation) to the linearized version of coframes, connection 1-forms, curvature and Cartan’s torsion, we construct a discrete version of linearized Riemann-Cartan geometry on any triangulation and determine its cohomology.","PeriodicalId":55151,"journal":{"name":"Foundations of Computational Mathematics","volume":"9 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146230775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yvonne Alama Bronsard, Xi Chen, Matthieu Dolbeault
{"title":"Spectrally Accurate Fully Discrete Schemes for Some Nonlocal and Nonlinear Integrable PDEs via Explicit Formulas","authors":"Yvonne Alama Bronsard, Xi Chen, Matthieu Dolbeault","doi":"10.1007/s10208-026-09740-2","DOIUrl":"https://doi.org/10.1007/s10208-026-09740-2","url":null,"abstract":"","PeriodicalId":55151,"journal":{"name":"Foundations of Computational Mathematics","volume":"1 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146101774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Discrete Trace Theory for Non-Conforming Polytopal Hybrid Discretisation Methods","authors":"Santiago Badia, Jerome Droniou, Jai Tushar","doi":"10.1007/s10208-025-09734-6","DOIUrl":"https://doi.org/10.1007/s10208-025-09734-6","url":null,"abstract":"In this work we develop a discrete trace theory that covers non-conforming hybrid discretization methods and holds on polytopal meshes. A notion of discrete trace seminorm is defined, and <jats:italic>trace</jats:italic> and <jats:italic>lifting</jats:italic> results with respect to a discrete <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$H^1$$</jats:tex-math> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msup> <mml:mi>H</mml:mi> <mml:mn>1</mml:mn> </mml:msup> </mml:math> </jats:alternatives> </jats:inline-formula> -seminorm on the hybrid fully discrete space are proven. Finally, we conduct a numerical test in which we compute the proposed discrete operators and investigate their spectrum to verify the theoretical analysis. The development of this theory is motivated by the design and analysis of preconditioners for hybrid methods, e.g., of substructuring domain decomposition type.","PeriodicalId":55151,"journal":{"name":"Foundations of Computational Mathematics","volume":"132 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145680181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Nullstellensatz and Positivstellensatz for Sparse Tropical Polynomial Systems","authors":"Marianne Akian, Antoine Béreau, Stéphane Gaubert","doi":"10.1007/s10208-025-09708-8","DOIUrl":"https://doi.org/10.1007/s10208-025-09708-8","url":null,"abstract":"","PeriodicalId":55151,"journal":{"name":"Foundations of Computational Mathematics","volume":"9 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145657532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}